Field of the Invention
The present invention relates to a projector and a projection screen, and more particularly, it relates to a projector and a projection screen each including a lens member splitting laser light and a diffusion member diffusing the laser light.
Description of the Background Art
A projector and a projection screen each including a lens member splitting laser light and a diffusion member diffusing the laser light are known in general, as disclosed in Japanese Patent Laying-Open No. 5-173094 (1993).
Japanese Patent Laying-Open No. 5-173094 discloses a laser display device (projector) including a laser light source (laser light generation portion) emitting laser light on the basis of an input image signal, a galvanometer mirror (projection portion) projecting an image by scanning the laser light emitted from the laser light source, and a rear projection type screen portion (projection screen) on which the image is projected. The rear projection type screen portion of this laser display device includes a lenticular lens (lens member) including a plurality of lens portions splitting the laser light scanned by the galvanometer mirror and a volume diffuser (diffusion member) arranged to be opposed to the lenticular lens, having an incident surface on which the laser light split by the lenticular lens is incident and crystalline powder (diffusion portion) diffusing the laser light incident from the incident surface. The incident surface of this volume diffuser is provided at the focal position of the lenticular lens along an optical axis with respect to the optical principal surface of the lenticular lens. Although not clearly described in the aforementioned Japanese Patent Laying-Open No. 5-173094, the crystalline powder of the volume diffuser is conceivably provided over the entire region of the volume diffuser from illustration in FIG. 3, and the laser light is diffused by the crystalline powder at the focal position.
In the laser display device according to the aforementioned Japanese Patent Laying-Open No. 5-173094, however, the laser light is sufficiently narrowed down at the focal position, so that the pitch of the crystalline powder conceivably becomes relatively large with respect to the spot diameter of the laser light at the focal position. In this case, the laser light is hardly diffused by the crystalline powder, so that diffusion components are reduced. Thus, the pattern of speckle noise is hardly averaged by synthesizing the diffusion components. Therefore, the effect of reducing speckle noise conceivably becomes insufficient.